The management of co-infection with HIV and hepatitis C virus (HCV) is complicated by viral and drug-drug interactions, treatment-related side effects, and the poor response to therapy of certain HCV genotypes. Current or past drug use may also have a negative impact. HEPAVIH (ANRS CO13) is an ongoing French cohort study of co-infected individuals which combines medical and socio-behavioral follow-up. This cohort study aims at analyzing the course of HCV infection and access to HCV treatment in HIV-HCV co-infected patients, using both clinical and patient-reported outcomes. This article documents the main lessons learned to date from the HEPAVIH data and published literature, while describing research prospects and needs requiring further investigation in the field of patient-reported outcomes.